This study investigates and compares the performance of an air conditioning system with conventional air-cooled condenser (CV-AC) and an air conditioning system with direct evaporative cooling on the condenser side (DEC-AC) utilizing four different cooling pad materials such as honeycomb structured cellulose, banana fibre, jute fibre, and cotton thread. The experiments were conducted at varying ambient air temperatures at 30 °C, 35 °C, 40 °C, and 45 °C DBT. The analysis focuses on key performance parameters including temperature drop across the cooling pad, cooling pad efficiency, heat rejection rate from the condenser, refrigerant condensing temperature and COP of the air conditioning system. Experimental results indicate that the DEC-AC system, utilizing all tested cooling pad materials, outperforms the CV-AC system. Regarding pad cooling efficiency under varying ambient air conditions, the cellulose pad exhibits the highest efficiency, ranging from 55.11 to 76.58%, followed by the banana fiber pad with an efficiency range of 38.4 to 54.62%, the jute fiber pad ranging from 31.68 to 47.51%, and the cotton thread pad demonstrating the lowest efficiency, ranging from 26.58 to 39.57%. Under the same ambient conditions, an air conditioning system employing direct evaporative cooling with a cellulose pad (aDEC-AC) demonstrated the highest performance, with a significant increase in heat rejection from the condenser of up to 68.33% and a reduction in condensing temperature of up to 8.41%. Followed by systems employing banana fibre (bDEC-AC), jute fibre (cDEC-AC), and cotton thread pads (dDEC-AC) recorded heat rejection improvements of up to 59.10%, 51.67%, and 43.17%, respectively, along with corresponding reductions in condensing temperature of up to 6.88%, 5.97%, and 5.46% all in comparison with CV-AC. Furthermore, the study also reveals that, as ambient air temperature increased, the COP of DEC-AC improved, with aDEC-AC achieving the highest increment in COP up to 27.93%, Followed by bDEC-AC, which achieved an increase of up to 18.81%, cDEC-AC showing an improvement of up to 17.17%, and dDEC-AC demonstrating the least increase of up to 15.8% compared to CV-AC. The operating costs for all cooling pads are approximately similar, with only minor variations. The cellulose pad incurs the highest cost of INR 7156, while the banana fibre pad has the lowest cost of INR 7046. These findings emphasize that incorporating direct evaporative cooling (DEC) system with air conditioning systems can substantially improve energy efficiency and system performance.

Enhancing air conditioning performance: effects of direct evaporative cooling with various pad materials on condensing temperature of R-22 and cycle efficiency

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发表日期：

2025年3月20日

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R. S. N. Sahai,
Umais M. Momin

摘要

This study investigates and compares the performance of an air conditioning system with conventional air-cooled condenser (CV-AC) and an air conditioning system with direct evaporative cooling on the condenser side (DEC-AC) utilizing four different cooling pad materials such as honeycomb structured cellulose, banana fibre, jute fibre, and cotton thread. The experiments were conducted at varying ambient air temperatures at 30 °C, 35 °C, 40 °C, and 45 °C DBT. The analysis focuses on key performance parameters including temperature drop across the cooling pad, cooling pad efficiency, heat rejection rate from the condenser, refrigerant condensing temperature and COP of the air conditioning system. Experimental results indicate that the DEC-AC system, utilizing all tested cooling pad materials, outperforms the CV-AC system. Regarding pad cooling efficiency under varying ambient air conditions, the cellulose pad exhibits the highest efficiency, ranging from 55.11 to 76.58%, followed by the banana fiber pad with an efficiency range of 38.4 to 54.62%, the jute fiber pad ranging from 31.68 to 47.51%, and the cotton thread pad demonstrating the lowest efficiency, ranging from 26.58 to 39.57%. Under the same ambient conditions, an air conditioning system employing direct evaporative cooling with a cellulose pad (^aDEC-AC) demonstrated the highest performance, with a significant increase in heat rejection from the condenser of up to 68.33% and a reduction in condensing temperature of up to 8.41%. Followed by systems employing banana fibre (^bDEC-AC), jute fibre (^cDEC-AC), and cotton thread pads (^dDEC-AC) recorded heat rejection improvements of up to 59.10%, 51.67%, and 43.17%, respectively, along with corresponding reductions in condensing temperature of up to 6.88%, 5.97%, and 5.46% all in comparison with CV-AC. Furthermore, the study also reveals that, as ambient air temperature increased, the COP of DEC-AC improved, with ^aDEC-AC achieving the highest increment in COP up to 27.93%, Followed by ^bDEC-AC, which achieved an increase of up to 18.81%, ^cDEC-AC showing an improvement of up to 17.17%, and ^dDEC-AC demonstrating the least increase of up to 15.8% compared to CV-AC. The operating costs for all cooling pads are approximately similar, with only minor variations. The cellulose pad incurs the highest cost of INR 7156, while the banana fibre pad has the lowest cost of INR 7046. These findings emphasize that incorporating direct evaporative cooling (DEC) system with air conditioning systems can substantially improve energy efficiency and system performance.